Foreigners can avoid paying tax on certain types of income in Sri Lanka by meeting specific conditions outlined in the Inland Revenue Act. Here are some ways based on the provided context:

1. Exemption on Foreign Currency Accounts: Profits and income accruing from moneys lying to the credit in any account opened by a resident guest in a commercial bank for the deposit of sums remitted to them in foreign currency from outside Sri Lanka are exempt from income tax.
2. Short Stays: If a person’s presence in Sri Lanka does not exceed an aggregate of thirty days for any year of assessment prior to April 1, 2013, such period is treated as if it had been spent outside Sri Lanka, which may affect tax residency status.
3. Government Employment Abroad: An individual employed by the Government of Sri Lanka who is resident in another country for the purposes of such employment, and their spouse, are deemed to be resident in Sri Lanka for tax purposes. This implies that if they are not in such employment, they may not be deemed tax residents.
4. Double Taxation Agreements: Foreigners can also benefit from double taxation agreements between Sri Lanka and their country of residence, which may provide relief or exemptions from certain taxes.
5. Foreign Tax Credit: A foreign tax credit is available for taxes paid in another country, which can be deducted against the Sri Lanka tax liability on a “source-by-source” and “asset-by-asset” basis, although excess foreign tax paid cannot be refunded or carried over.

It is important for foreigners to consult with a tax professional or refer to the Inland Revenue Act for detailed advice tailored to their specific circumstances.